This application claims the benefit of Korean Patent Application No. 10-2004-0071224, filed on Sep. 7, 2004, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference.
1. Field of the Invention
The present invention relates to an optical detection apparatus for multi-channel multi-color measurement and a multi-channel sample analyzer employing the same, and more particularly, to an optical detection apparatus which can measure multi-channel samples at high speed and various wavelengths using an optical detector and a multi-channel sample analyzer employing the same.
2. Description of the Related Art
A method of analyzing components of a sample which includes irradiating a specific wavelength of light onto the sample and then detecting a spectrum of light which is emitted from the sample is well known. For example, the respective bases of DNA can be labeled with fluorescent dyes having different emission wavelengths, and then the intensity light emitted from the fluorescent dyes is analyzed, thereby identifying the base sequence of the DNA.
FIG. 1 is a schematic diagram of a conventional fluorescent analyzer 100. Referring to FIG. 1, the conventional fluorescent analyzer 100 includes an optical unit 110 for irradiating light onto a sample 130 and a detection unit 120 for detecting light emitted from the sample 130. The optical unit 110 generally includes a light source 112, a dichroic mirror 114, an objective lens 115, and a sample holder 117. The detection unit 120 includes an optical detector 125, for example, a photo mutiplier tube (PMT), and a filter 121 which transmits a specific wavelength of light, etc. The light source 112 may include various sources, such as a halogen lamp, a light-emitting diode (LED), a laser, etc. Light emitted from the light source 112 is reflected by the dichroic mirror 114 and is partially absorbed by the sample 130 on the sample holder 117. The light emitted from the sample 130 is transmitted through the dichroic mirror 114 and enters the detection unit 120. The light which enters the detection unit 120 is transmitted through the filter 121, thus having a specific wavelength and the optical detector 125 detects the intensity of light having the specific wavelength. By analyzing the intensity of the fluorescence light emitted from the sample by varying the wavelength property of the filter 121 or the light source 110, the analyte of the sample can be identified.
Recently, to increase the efficiency of analyzing a sample and determine the identity of the sample at high speed, a multi-channel sample analyzer, which can analyze a plurality of samples at once, has been developed. Multi-channel sample analysers can be roughly classified into apparatuses which determine a plurality of samples simultaneously using a plurality of optical detectors and apparatuses which determine a plurality of samples sequentially using an optical detector.
Examples of the apparatuses which determine a plurality of samples simultaneously using a plurality of optical detectors include one which uses a number of separate optical detectors equal to the number of the samples, and the optical detectors detect the light emitted from the respective samples (for example, Cepheid Smart CyclerR) and one in which a large area of light is irradiated to a plurality of samples at a time and a CCD having a large area detects the lights emitted from the samples (for example, ABI Prism 7000R and BioRad iCyclerR). However, when the number of separate optical detectors is equal to the number of the samples, filters which can cover a band of wavelength to be examined are disposed in front of the respective optical detectors. Thus, too many optical detectors and filters are used relative to the number of samples. On the other hand, when the CCD is used, only one filter wheel may be used. However, a CCD having a large area and a high accuracy required for fluorescent analysis is very expensive, thus increasing the production costs of the multi-channel sample analyzer and being unsuitable for small analyzers. Referring to FIG. 2, a rotating filter wheel is generally disposed in front of the CCD to perform multi-channel analysis using a variety of wavelengths. However, since a frame rate (the number of images which a CCD reads per second), which is related to a resolution of the CCD measurement, is limited, an increase in speed of the filter wheel is limited. Thus, there is still a limit when measuring many wavelengths at high speed.
In an apparatus for determining a plurality of samples sequentially using an optical detector, generally, a plurality of samples are placed on a sample holder and the samples are measured by scanning. As described above, to perform the spectroscopic analysis of a sample at many wavelengths, the filter wheel should be rotated. Thus, a total measuring time calculated by multiplying a scanning time of the sample by a rotation time of the filter wheel can be increased.
Thus, there is a need for a detection unit which can detect a plurality of samples at high speed and various wavelengths using an optical detector and a filter wheel.